Marks Mac_ios external_ui_integration_test_ios to be unflaky (#106041)

diff --git a/.ci.yaml b/.ci.yaml
index 70c59d3..606da99 100644
--- a/.ci.yaml
+++ b/.ci.yaml
@@ -3233,7 +3233,6 @@
     scheduler: luci
 
   - name: Mac_ios external_ui_integration_test_ios
-    bringup: true # Flaky https://github.com/flutter/flutter/issues/103057
     recipe: devicelab/devicelab_drone
     presubmit: false
     timeout: 60